U.S. patent application number 11/955032 was filed with the patent office on 2009-06-18 for semiconductor with active component and method for manufacture.
This patent application is currently assigned to INFINEON TECHNOLOGIES AUSTRIA AG. Invention is credited to Franz Hirler, Walter Rieger.
Application Number | 20090152667 11/955032 |
Document ID | / |
Family ID | 40690122 |
Filed Date | 2009-06-18 |
United States Patent
Application |
20090152667 |
Kind Code |
A1 |
Rieger; Walter ; et
al. |
June 18, 2009 |
Semiconductor with active component and method for manufacture
Abstract
A semiconductor with active component and method for
manufacture. One embodiment provides a semiconductor component
arrangement having an active semiconductor component and a
semiconductor body having a first semiconductor zone, a third
semiconductor zone, and also a drift zone arranged between the
first semiconductor zone and the third semiconductor zone. A
patterned fourth semiconductor zone doped complementarily to the
drift zone is arranged in the drift zone. A potential control
structure is provided, which is connected to the patterned fourth
semiconductor zone. The potential control structure is designed to
connect the patterned fourth semiconductor zone, in the off state
of the semiconductor component, to an electrical potential lying
between the electrical potential of the first semiconductor zone
and the electrical potential of the third semiconductor zone.
Inventors: |
Rieger; Walter;
(Arnoldstein, AT) ; Hirler; Franz; (Isen,
DE) |
Correspondence
Address: |
DICKE, BILLIG & CZAJA
FIFTH STREET TOWERS, 100 SOUTH FIFTH STREET, SUITE 2250
MINNEAPOLIS
MN
55402
US
|
Assignee: |
INFINEON TECHNOLOGIES AUSTRIA
AG
Villach
DE
|
Family ID: |
40690122 |
Appl. No.: |
11/955032 |
Filed: |
December 12, 2007 |
Current U.S.
Class: |
257/488 ;
257/E23.002 |
Current CPC
Class: |
H01L 29/0634 20130101;
H01L 29/0696 20130101; H01L 29/0626 20130101; H01L 2924/0002
20130101; H01L 29/866 20130101; H01L 29/7811 20130101; H01L 29/0878
20130101; H01L 29/66348 20130101; H01L 29/7804 20130101; H01L
29/66734 20130101; H01L 29/0623 20130101; H01L 29/7397 20130101;
H01L 29/7813 20130101; H01L 29/7802 20130101; H01L 29/41766
20130101; H01L 29/861 20130101; H01L 29/402 20130101; H01L 29/407
20130101; H01L 29/8611 20130101; H01L 29/7808 20130101; H01L
2924/0002 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
257/488 ;
257/E23.002 |
International
Class: |
H01L 23/58 20060101
H01L023/58 |
Claims
1. (canceled)
2-40. (canceled)
41. A semiconductor component arrangement comprising an active
semiconductor component which can assume an on state and an off
state and comprising: a semiconductor body comprising a first
semiconductor zone, a third semiconductor zone, and also a second
semiconductor zone of a first conduction type, the second
semiconductor zone being arranged between the first semiconductor
zone and the third semiconductor zone and being formed as a drift
zone; a patterned fourth semiconductor zone arranged in the second
semiconductor zone of a second conduction type, which is
complementary to the first conduction type; a first potential
control structure, connected to the patterned fourth semiconductor
zone and is configured to feed to the patterned fourth
semiconductor zone in the off state of the semiconductor component
an electrical potential lying between the electrical potential of
the first semiconductor zone and the electrical potential of the
third semiconductor zone, and/or is connected to the patterned
fourth semiconductor zone and is configured to connect the
patterned fourth semiconductor zone, upon the semiconductor
component being switched on, for discharging the fourth
semiconductor zone, to an electrical potential lying between the
electrical potential of the first semiconductor zone and the
electrical potential of the third semiconductor zone.
42. The semiconductor component arrangement of claim 41, wherein
the first potential control structure comprises a voltage divider
connected between the first semiconductor zone and the third
semiconductor zone.
43. The semiconductor component arrangement of claim 41, wherein
the first potential control structure comprises a resistor
connected to the first semiconductor zone and to the patterned
fourth semiconductor zone.
44. The semiconductor component arrangement of claim 41, wherein
the first potential control structure comprises: a ninth
semiconductor zone of the second conduction type, which is
connected to the patterned fourth semiconductor zone; and a third
electrode, which is applied to the semiconductor body and which is
connected to the ninth semiconductor zone.
45. The semiconductor component arrangement of claim 44, wherein
the semiconductor component comprises: an active component region,
wherein the ninth semiconductor zone is arranged outside the active
component region.
46. The semiconductor component arrangement of claim 45, wherein
the semiconductor component comprises: two active component
regions, between which the ninth semiconductor zone is
arranged.
47. The semiconductor component arrangement of claim 44, wherein
the first potential control structure comprises: a first diode
comprising an anode and a cathode, wherein the anode is connected
to the third semiconductor zone and wherein the cathode is
connected to the ninth semiconductor zone.
48. The semiconductor component arrangement of claim 44, wherein
the first potential control structure comprises: a seventh
semiconductor zone of the first conduction type, which is connected
to the second semiconductor zone and to the third electrode.
49. The semiconductor component arrangement of claim 48, wherein
the semiconductor component comprises: an active component region,
wherein the seventh semiconductor zone is arranged outside the
active component region.
50. The semiconductor component arrangement of claim 48, wherein
the semiconductor component comprises: a first field electrode,
arranged between the second semiconductor zone and the seventh
semiconductor zone, and electrically insulated from the second
semiconductor zone and from the seventh semiconductor zone by means
of a dielectric, and which extends into the semiconductor body in a
direction of the first semiconductor zone.
51. The semiconductor component arrangement of claim 48, wherein
the semiconductor component comprises: a second field electrode,
which is arranged between the ninth semiconductor zone and the
seventh semiconductor zone and is electrically insulated from the
ninth semiconductor zone and from the seventh semiconductor zone by
means of a dielectric, and which extends into the semiconductor
body in a direction of the first semiconductor zone.
52. The semiconductor component arrangement of claim 44, wherein
the semiconductor component comprises: a lateral edge; and a third
field electrode, which is arranged between the lateral edge and the
ninth semiconductor zone and is electrically insulated from the
ninth semiconductor zone by means of a dielectric, and which
extends into the semiconductor body in a direction of the first
semiconductor zone.
53. The semiconductor component arrangement of claim 44,
comprising: a patterned fifth semiconductor zone--arranged in the
second semiconductor zone--of the second conduction type; a second
potential control structure, connected to the patterned fifth
semiconductor zone and is designed to feed to the patterned fifth
semiconductor zone in the off state of the semiconductor component
an electrical potential lying between the electrical potential of
the first semiconductor zone and the electrical potential of the
patterned fourth semiconductor zone, and is connected to the
patterned fifth semiconductor zone and is designed to connect the
patterned fifth semiconductor zone, upon the semiconductor
component being switched on, for discharging the fifth
semiconductor zone, to an electrical potential lying between the
electrical potential of the first semiconductor zone and the
electrical potential of the third semiconductor zone.
54. A semiconductor component arrangement comprising an active
semiconductor component which can assume an on state and an off
state comprising: a semiconductor body comprising a first
semiconductor zone, a third semiconductor zone, and also a second
semiconductor zone of a first conduction type, the second
semiconductor zone being arranged between the first semiconductor
zone and the third semiconductor zone and being formed as a drift
zone; a patterned fourth semiconductor zone--arranged in the second
semiconductor zone--of a second conduction type, which is
complementary to the first conduction type; and a resistor
connected to the first semiconductor zone and to the patterned
fourth semiconductor zone.
55. A semiconductor component arrangement comprising an active
semiconductor component which can assume an on state and an off
state comprising: a semiconductor body comprising a first
semiconductor zone, a third semiconductor zone, and also a second
semiconductor zone of a first conduction type, the second
semiconductor zone being arranged between the first semiconductor
zone and the third semiconductor zone and being formed as a drift
zone; a patterned fourth semiconductor zone--arranged in the second
semiconductor zone--of a second conduction type, which is
complementary to the first conduction type; and a first diode, the
anode of which is connected to the third semiconductor zone and the
cathode of which is connected to the patterned fourth semiconductor
zone.
56. The semiconductor component arrangement of claim 55 comprising
wherein a resistor connected to the first semiconductor zone and to
the patterned fourth semiconductor zone.
57. A semiconductor component arrangement comprising an active
semiconductor component which can assume an on state and an off
state comprising: a semiconductor body comprising a first
semiconductor zone, a third semiconductor zone, and also a second
semiconductor zone of a first conduction type, the second
semiconductor zone being arranged between the first semiconductor
zone and the third semiconductor zone and being formed as a drift
zone; a patterned fourth semiconductor zone--arranged in the second
semiconductor zone--of a second conduction type, which is
complementary to the first conduction type; and a seventh
semiconductor zone of the first conduction type, which is
electrically connected, on the one hand, to the patterned fourth
semiconductor zone and, on the other hand, to a first location of
the second semiconductor zone, the first location being arranged at
a distance from the third semiconductor zone and being arranged
between the third semiconductor zone and the patterned fourth
semiconductor zone.
58. The semiconductor component arrangement of claim 57, wherein
the fourth semiconductor zone comprises the electrical potential of
the first location when the semiconductor component is in the off
state.
59. The semiconductor component arrangement of claim 57 comprising
wherein a thirteenth semiconductor zone of the second conduction
type, connected to the patterned fourth semiconductor zone and
together with the seventh semiconductor zone forms a pn
junction.
60. The semiconductor component arrangement of claim 59 comprising
wherein a fourteenth semiconductor zone of the first conduction
type, connected to the patterned fourth semiconductor zone and
together with the thirteenth semiconductor zone forms a pn
junction.
61. The semiconductor component arrangement of claim 57 comprising
wherein a patterned fifth semiconductor zone of the second
conduction type, arranged between the patterned fourth
semiconductor zone and the first semiconductor zone in the second
semiconductor zone.
62. The semiconductor component arrangement of claim 61 comprising
wherein a tenth semiconductor zone of the first conduction type,
connected to the patterned fifth semiconductor zone and, to a
second location of the second semiconductor zone, the second
location being at a distance from the third semiconductor zone and
being arranged between the patterned fourth semiconductor zone and
the patterned fifth semiconductor zone.
63. The semiconductor component arrangement of claim 62, wherein
the tenth semiconductor zone comprises the electrical potential of
the second location when the semiconductor component is in the off
state.
64. The semiconductor component arrangement of claim 62 comprising
wherein a second diode, the anode of which is connected to the
patterned fourth semiconductor zone and the cathode of which is
connected to the patterned fifth semiconductor zone.
65. A semiconductor component arrangement comprising an active
semiconductor component which can assume an on state and an off
state and comprising: a semiconductor body comprising a first
semiconductor zone, a third semiconductor zone, and also a second
semiconductor zone of a first conduction type, the second
semiconductor zone being arranged between the first semiconductor
zone and the third semiconductor zone and being formed as a drift
zone; a patterned fourth semiconductor zone arranged in the second
semiconductor zone of a second conduction type, which is
complementary to the first conduction type; means for providing a
first potential control structure, connected to the patterned
fourth semiconductor zone and is designed to feed to the patterned
fourth semiconductor zone in the off state of the semiconductor
component an electrical potential lying between the electrical
potential of the first semiconductor zone and the electrical
potential of the third semiconductor zone
Description
BACKGROUND
[0001] In the off state, power semiconductor components must take
up high voltages, but are nevertheless intended to have a low on
resistance. The reverse voltage strength and the on resistance of a
power semiconductor component are competing variables, however,
that is to say that the on resistance of a power semiconductor
component generally also rises with the reverse voltage strength of
the component. Therefore, there is a need for power semiconductor
components which have a lowest possible on resistance for a
predetermined reverse voltage strength.
SUMMARY
[0002] One or more embodiments described below relate to a
semiconductor component arrangement including an active
semiconductor component, which can assume an on state and an off
state. The semiconductor component has a semiconductor body having
a first semiconductor zone, a third semiconductor zone, and also a
second semiconductor zone of a first conduction type, the second
semiconductor zone being arranged between the first semiconductor
zone and the third semiconductor zone and being formed as a drift
zone. A patterned fourth semiconductor zone of a second conduction
type, which is complementary to the first conduction type, is
arranged in the second semiconductor zone. Furthermore, a potential
control structure is provided, which is connected to the patterned
fourth semiconductor zone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Various examples are explained in more detail below with
reference to figures. Said The figures and the associated
description serve to afford a better understanding of the basic
principle. In the figures, identical reference symbols designate
identical elements with the same meaning. For reasons of
representability, the figures shown illustrated are not true to
scale.
[0004] FIG. 1 illustrates a vertical section through a vertical
semiconductor component formed as a diode with a patterned
semiconductor zone.
[0005] FIG. 2 illustrates a vertical section through an edge region
of a vertical semiconductor component formed as a trench
transistor, a patterned semiconductor zone being arranged in the
drift zone of the component.
[0006] FIG. 3 illustrates a horizontal section through an edge
portion of the trench transistor illustrated in FIG. 2, in a
sectional plane B1, perpendicular to the vertical direction,
through the patterned semiconductor zone.
[0007] FIG. 4 illustrates a horizontal section through the edge
section of a trench transistor illustrated in FIG. 2, in a
sectional plane A1, perpendicular to the vertical direction,
through the gate electrodes of the trench transistor.
[0008] FIG. 5 illustrates a vertical section through an edge
portion of a vertical trench transistor with two patterned
semiconductor zones which are arranged in the drift zone and are at
a distance from one another.
[0009] FIG. 6 illustrates a vertical section through the edge
region of a trench transistor in accordance with FIG. 2 in which
the patterned semiconductor zone is connected by using an
additional sinker arranged between two adjacent active component
portions.
[0010] FIG. 7 illustrates a vertical section through the edge
region of a trench transistor which has a basic construction in
accordance with FIG. 2, but in which the potential control
structure has a further semiconductor zone doped complementarily to
the drift zone.
[0011] FIG. 8 illustrates a vertical section through the edge
region of a trench transistor having a basic construction in
accordance with FIG. 2, but in which the potential control
structure has a zener diode integrated into the semiconductor
body.
[0012] FIG. 9 illustrates a vertical section through an edge
portion of a trench transistor in which the patterned semiconductor
zone is connected to the source zone of the trench transistor by
using an external diode.
[0013] FIG. 10 illustrates a vertical section through an edge
portion of a trench transistor which has two patterned
semiconductor zones which are at a distance from one another in the
vertical direction and which are respectively connected via a diode
to the source zone.
[0014] FIG. 11 illustrates a vertical section through an edge
portion of a vertical trench transistor in accordance with FIG. 2,
but in which a dopant of the first conduction type is additionally
introduced into the drift zone between two adjacent portions of the
patterned semiconductor zone, the dopant having only a very low
diffusion rate.
[0015] FIG. 12 illustrates a horizontal section through an edge
portion of the trench transistor illustrated in FIG. 11, in a plane
B2, perpendicular to the vertical direction, through the patterned
semiconductor zone.
[0016] FIG. 13 illustrates various processes of a method for
producing a trench transistor in accordance with FIG. 5.
[0017] FIG. 14 illustrates a vertical section through a planar
diode with an edge termination having a field plate structure,
wherein the potential control structure includes a zener diode
integrated into the semiconductor body of the planar diode.
[0018] FIG. 15 illustrates a vertical section through a planar
diode with an edge termination having a field plate structure, and
a patterned anode.
[0019] FIG. 16 illustrates a vertical section through a planar
transistor in which the potential control structure includes a
zener diode integrated into the semiconductor body of the
diode.
[0020] FIG. 17 illustrates a vertical section through an edge
portion of a planar transistor in the drift zone of which are
arranged two patterned semiconductor zones which are doped
complementarily to the drift zone and are at a distance from one
another.
DETAILED DESCRIPTION
[0021] In the following Detailed Description, reference is made to
the accompanying drawings, which form a part hereof, and in which
is shown by way of illustration specific embodiments in which the
invention may be practiced. In this regard, directional
terminology, such as "top," "bottom," "front," "back," "leading,"
"trailing," etc., is used with reference to the orientation of the
Figure(s) being described. Because components of embodiments can be
positioned in a number of different orientations, the directional
terminology is used for purposes of illustration and is in no way
limiting. It is to be understood that other embodiments may be
utilized and structural or logical changes may be made without
departing from the scope of the present invention. The following
detailed description, therefore, is not to be taken in a limiting
sense, and the scope of the present invention is defined by the
appended claims.
[0022] It is to be understood that the features of the various
exemplary embodiments described herein may be combined with each
other, unless specifically noted otherwise.
[0023] FIG. 1 illustrates a vertical section through a portion near
the edge of a semiconductor component formed as a diode, in a
sectional plane V1, which can be seen from FIG. 3. The diode
includes a semiconductor body 100 having a front side 101 and a
rear side 102 opposite the front side 101 in a vertical direction
v. Arranged in the semiconductor body 100, proceeding from the rear
side 102 toward the front side 101, are a heavily n-doped first
semiconductor zone 11, a weakly n-doped second semiconductor zone
12 formed as a drift zone, and a p-doped third semiconductor zone
13.
[0024] The diode furthermore includes an active component region
100a, which is at a distance from the lateral edge 103 of the
semiconductor body 100 and which extends over the entire component
in the vertical direction v and over the same region as the third
semiconductor zone 13 and/or the second semiconductor zone 12 in a
first lateral direction r1, perpendicular to the vertical direction
v.
[0025] Furthermore, a first electrode 91, which is formed as an
anode electrode, is applied to the front side 101, the first
electrode being electrically connected to the third semiconductor
zone 13. Dielectric layers 26 and 27 are additionally arranged
between the semiconductor body 100 and the source electrode 91. An
electrode 92, which is formed as a cathode electrode, is applied to
the rear side 102, the electrode being electrically connected to
the first semiconductor zone 11. An anode terminal A connected to
the anode electrode 91 and a cathode terminal D connected to the
cathode electrode 92 are provided for external circuitry connection
of the diode.
[0026] A patterned fourth semiconductor zone 4, which is doped
complementarily to the drift zone 12, is embedded into the drift
zone 12, and extends over a layer 18 of the semiconductor body 100
in the vertical direction v and is at a distance from the front
side 101 and also from the pn junction formed between the second
semiconductor zone 12 and the third semiconductor zone 13.
[0027] In the example illustrated, the patterned fourth
semiconductor zone 4 has portions 40, 41, 42, and also further
portions, not illustrated, which are arranged in the active
component region 100a at a distance from one another in one of the
first lateral direction r1 and in a second lateral direction r2,
perpendicular to the vertical direction v and to the first lateral
direction r1, such that a portion 125 of the drift zone 12 is
respectively arranged between two adjacent portions from among the
portions 40, 41, 42. The portions 40, 41, 42 and also the further
portions (not illustrated) of the patterned fourth semiconductor
zone 4 are electrically conductively connected to one another and
can be formed for example as a continuous p-doped semiconductor
region.
[0028] In principle, such a patterned fourth semiconductor zone 4,
irrespective of the type of component, in the off state of the
component, is not floating but rather is connected to an electrical
potential. Such a patterned fourth semiconductor zone 4 can be
designed in such a way that it is depleted at a predetermined
reverse voltage present at the component. As an alternative to
this, however, it can also be doped so heavily that it is not
depleted at the predetermined reverse voltage present. The doping
and the geometry of such a patterned fourth semiconductor zone 4
are chosen such that the second semiconductor zone 12, in the off
state of the component, no longer contains any free charge carriers
at least in a layer 18 that also includes the patterned fourth
semiconductor zone 4.
[0029] In the illustrated off state of the diode, that is to say if
the cathode terminal K carries an electrical potential U.sub.K that
is higher than an electrical potential U.sub.A present at the anode
terminal A, the patterned fourth semiconductor zone 4 is fed an
electrical potential U.sub.4 lying between the electrical
potentials U.sub.A and U.sub.K. On account of the potential
differences between the portions 40, 41, 42 and the second
semiconductor zone 12, space charge zones 29 form, when the diode
is in the off state, at the pn junctions between the drift zone 12
and the portions 40, 41, 42 of the patterned fourth semiconductor
zone 4, which space charge zones pinch off a channel formed in the
portions 125 of the drift zone 12. The space charge zones 29 serve
to largely deplete the second semiconductor zone 12 in the layer 18
of the patterned fourth semiconductor zone 4 when the component is
in the off state, thereby increasing the blocking capability of the
diode in comparison with a diode which is constructed identically
but which does not have such a patterned fourth semiconductor zone
4. Moreover, the second semiconductor zone 12 of a component having
such a patterned fourth semiconductor zone 4 can be doped more
heavily in comparison with a conventional component with the same
maximum reverse voltage, whereby the on resistance of the diode
decreases.
[0030] In the off state of the diode illustrated, the patterned
fourth semiconductor zone 4 is connected to an electrical potential
U.sub.4 which the second semiconductor zone 12 has at a location
128 arranged nearer the front side 101 and nearer the pn junction
formed between the second semiconductor zone 12 and the third
semiconductor zone 13 than the patterned fourth semiconductor zone
4. In the case of the exemplary embodiment in accordance with FIG.
1, the location 128 is arranged directly below the dielectric 26 of
a first field electrode 961 arranged in a trench, which electrode
terminates the active component region 100a toward the lateral edge
103 of the semiconductor body 100. When the component is in the off
state, the potential U.sub.4 present at the location 128 is also
present essentially unchanged at a third electrode 93, which is
applied to the front side 101 of the semiconductor body 100 and
which is connected to the second semiconductor zone 12 via a
seventh semiconductor zone 129 and an eighth semiconductor zone 31.
The seventh semiconductor zone 129 and the eighth semiconductor
zone 31 are arranged outside the active component region 100a and
have the conduction type of the second semiconductor zone 12,
wherein the eighth semiconductor zone 31 is doped more heavily than
the seventh semiconductor zone 129. The third electrode 93 is
furthermore connected to a ninth semiconductor zone 49 ("sinker"),
which is doped complementarily to the second semiconductor zone 12
and which, for its part, is connected to the patterned fourth
semiconductor zone 4 and electrically connects the latter to the
third electrode 93. The ninth semiconductor zone 49 can be doped in
such a way that it is not depleted at least in a portion situated
between the third electrode 93 and the layer 18, even at those
voltages at which the avalanche breakdown occurs at the pn junction
formed between the second semiconductor zone 12 and the third
semiconductor zone 13.
[0031] On account of the potential control structure, the patterned
fourth semiconductor zone 4 is at the electrical potential U.sub.4
when the diode is in the off state. The first field electrode 961
serves to electrically decouple the seventh semiconductor zone 129
from a front-side portion of the second semiconductor zone 12, the
portion being located laterally alongside the first field electrode
961 and the dielectric 26 thereof. For this purpose, the first
field electrode 961 is arranged between the seventh semiconductor
zone 129 and the second semiconductor zone 12 and extends into the
semiconductor body 100 in a direction of the first semiconductor
zone 11 proceeding from the front side 101. The potential fed to
the patterned fourth semiconductor zone 4 when the diode is in the
off state can be set by using the depth t961 into which the first
field electrode 961 including the dielectric 26 surrounding it
extends into the semiconductor body 100 in the vertical direction
v. The greater the depth t961 is chosen to be, the less the
electrical potential of the patterned fourth semiconductor zone 4
differs from the electrical potential of the portions 125 of the
drift zone 12.
[0032] Moreover, the potential control structure, in the same way
as the potential control structures in the subsequent exemplary
embodiments, includes an optional resistor 80, which electrically
connects the patterned fourth semiconductor zone 4 to the first
semiconductor zone 11, for example via the ninth semiconductor zone
49, the third electrode 93 and the second electrode 92. In this
case, the resistor 80 can be integrated into the semiconductor body
100 or be arranged outside the semiconductor body 100. A resistor
80 formed within the semiconductor body 100 can be realized for
example by one or a plurality of doped semiconductor zones, wherein
pn junctions can optionally be formed between such doped
semiconductor zones.
[0033] The potential control structure is dimensioned in such a way
that at a predetermined reverse voltage dropped between the anode
terminal A and the cathode terminal K, for example 100 V to 400 V,
on account of the electrical potential U.sub.4 fed to the patterned
fourth semiconductor zone 4, all sections 125 of the drift zone 12
which penetrate through the layer 18 of the patterned fourth
semiconductor zone 4 are completely covered by the space charge
zones 29. This has the effect that the second semiconductor zone 12
is largely depleted of charge carriers in the layer 18 which
extends as far as the lateral edge 103 of the semiconductor body
100 in each lateral direction r1, r2 perpendicular to the vertical
direction v. The depleted portions of the second semiconductor zone
12 can take up a high reverse voltage. As a result of this "active"
depletion of free charge carriers from those portions of the second
semiconductor zone 12 which are situated in the layer 18, the
second semiconductor zone 12, at least in the portions, can be
doped more highly, for example with a dopant concentration of
10.sup.14 cm.sup.-3 to 10.sup.18 cm.sup.-3, than in the case of a
diode which is constructed identically but which does not have a
patterned fourth semiconductor zone 4. This increased doping by
comparison with a conventional diode brings about a reduction of
the on resistance.
[0034] Apart from its function of connecting the patterned fourth
semiconductor zone 4 to a defined electrical potential in the
off-state case, the potential control structure can also be
designed to discharge the patterned semiconductor zone 4 upon the
component being switched on, that is to say upon the transition
from the off state illustrated to the on state.
[0035] The potential control structure explained above was chosen
by way of example in order to explain the functioning of a
component having a patterned fourth semiconductor zone 4. In
principle, the potential control structure illustrated, in an
identical or modified form, can also be applied to other
semiconductor components having a drift zone, for example to
MOSFETs or IGBTs. As an alternative to this, the potential control
structure of a diode or of some other semiconductor component can
be configured totally differently from the potential control
structure explained, as long as the patterned fourth semiconductor
zone 4, when the component is in the off state, has a potential
which lies between the electrical potentials which the drift zone
12 has between the third semiconductor zone 13 and the patterned
semiconductor zone 4.
[0036] FIG. 2 illustrates a vertical section through the edge
region of a semiconductor component formed as a vertical trench
transistor (trench MOSFET), in a sectional plane V1 which can be
seen from FIGS. 3 and 4. As an alternative to the exemplary
embodiment illustrated, the semiconductor component can also be
formed as an IGBT. In the case of an IGBT, the heavy n-type doping
of the first semiconductor zone 11 formed as a drain zone should be
replaced by a heavy p-type doping.
[0037] In the case of this trench transistor, the function and the
construction of the potential control structure and of the
patterned fourth semiconductor zone 4 are identical to the function
and the construction of the potential control structure and of the
patterned fourth semiconductor zone 4 of the diode in accordance
with FIG. 1.
[0038] In contrast to the diode in accordance with FIG. 1, the
trench transistor in accordance with FIG. 2 has a cell structure
formed in the active component region and having one or a plurality
of parallel-connected active transistor cells arranged at a
distance from one another in the first lateral direction r1. Owing
to the cell structure, the transistor portion 100a having the
active transistor cells is also referred to as "active cell
region". In the first lateral direction r1, there are adjacent to
the illustrated active transistor cell having the gate electrode 95
even further active transistor cells (not illustrated) having gate
electrodes 95 of this type. The gate electrodes 95 are arranged in
a trench having the depth t95--relative to the front side 101. In
the case of a semiconductor component having such a trench
structure, the distance t4 can be chosen for example to be less
than 1 times to 2 times the depth t95 of the gate electrodes
95.
[0039] In each of the transistor cells, a p-doped sixth
semiconductor zone 16 formed as a body zone and also a heavily
n-doped third semiconductor zone 13 formed as a source zone are
arranged between the second semiconductor zone 12 and the front
side 101. In a departure from the diode in accordance with FIG. 1,
the third semiconductor zone 13 is not p-doped but rather n-doped
in the case of the present MOSFET. Furthermore, the first electrode
91 applied to the front side 101 represents a source electrode that
is electrically connected to the third semiconductor zone 13. The
second electrode 92 applied to the rear side 102 represents a drain
electrode that is electrically connected to the first semiconductor
zone 11. Moreover, a source terminal S connected to the source
electrode 91 and a drain terminal D connected to the drain
electrode 92 are provided for external circuitry connection of the
transistor.
[0040] In order to control an electric current between the source
terminal S and the drain terminal D, in one embodiment in order to
switch the current on or off, the gate electrodes 95 are provided.
The latter extend into the second semiconductor zone 12 in a
direction of the first semiconductor zone 11, but are at a distance
from the first semiconductor zone 11. A gate dielectric 25 is
provided for electrically insulating the gate electrodes 95 from
the second semiconductor zone 12, the sixth semiconductor zone 16
and the third semiconductor zone 13.
[0041] Alongside the first field electrode 961 already explained,
which terminates the active component region 100a toward the
lateral edge 103 of the semiconductor body 100, a second field
electrode 962 and a third field electrode 963 are also provided,
which extend into the semiconductor body 100 in a direction of the
first semiconductor zone 11 proceeding from the front side 101 and
are a distance from the first semiconductor zone 11. The second
field electrode 962 is arranged between the ninth semiconductor
zone 49 and the seventh semiconductor zone 129 and is electrically
insulated from that of the second semiconductor zone 12 by using a
dielectric 26. The third field electrode 963 is arranged between
the lateral edge 103 of the semiconductor body 100 and the ninth
semiconductor zone 49 and is electrically insulated from that of
the ninth semiconductor zone 49 by using a dielectric 26.
[0042] If only precisely one patterned semiconductor zone such as
the present patterned fourth semiconductor zone 4 is provided in
the semiconductor component, for example all of the field
electrodes 961, 962, 963 can be at source potential, that is to say
the potential of the third semiconductor zone 13 and the first
electrode 91. As an alternative to this, the field electrodes 961,
962, 963 of the component can for example also all be arranged in
floating fashion in the semiconductor body 1.
[0043] FIG. 3 illustrates a horizontal section through a portion of
the diode illustrated in FIG. 1 or of the trench transistor
illustrated in FIG. 2, in a sectional plane B1 perpendicular to the
vertical direction v. This horizontal section is moreover identical
to the horizontal sections through sectional planes B2, B3 and B4
such as are illustrated in FIGS. 11, 7 and 8, respectively.
[0044] It can be seen from the sectional view in accordance with
FIG. 3 that the ninth semiconductor zone 49 and also the portions
40, 41 and 42 of the patterned fourth semiconductor zone 4 can be
formed in strip-like fashion and can run in a second lateral
direction r2 perpendicular both to the vertical direction v and to
the first lateral direction r1. Moreover, the patterned fourth
semiconductor zone 4 can have a reticulated or lattice-like
structure as in the present case. As an alternative thereto, other
structures, e.g., strip-like, meander-like, comb-like or comb-like
intermeshing, structures are also conceivable. What is crucial is
that the patterned fourth semiconductor zone 4 pervades the second
semiconductor zone 12 sufficiently densely.
[0045] In order to electrically connect the sinker 49 to the
portions 40, 41 and 42 and also to further portions (not
illustrated) of the patterned fourth semiconductor zone 4,
connecting webs 48 are provided, which extend in the first lateral
direction r1 and which connect the fourth semiconductor zone 49 to
the first 40 of the strip-like portions 40, 41, 42, and adjacent
strip-like portions 41, 42 to one another. As can be seen from FIG.
3, the patterned fourth semiconductor zone 4 can be formed as a
continuous semiconductor zone through which the portions of the
second semiconductor zone 12 extend in a pillar-like manner.
[0046] FIG. 4 illustrates the same transistor edge portion as FIGS.
2 and 3 in a sectional plane A1--which can likewise be seen from
FIG. 2 with respect to the sectional plane B1--through the gate
electrodes 95 and through the field electrodes 961, 962, 963. The
underlying sectional view known from FIG. 3 is additionally
illustrated by dashed lines. This horizontal section is moreover
identical to horizontal sections through sectional planes A3 and A4
such as are illustrated in FIGS. 7 and 8, respectively.
[0047] In the case of the transistor in accordance with FIG. 4, the
first, the second and the third field electrode 961, 962 and 963,
respectively, and also the active cells of the transistor with
their gate electrodes 95 are formed as strips running in the second
lateral direction r2. Comparison of FIGS. 3 and 4 reveals that the
portions 40, 41, 42 of the patterned fourth semiconductor zone 4
and the active cells with the gate electrodes 95 run in the same
lateral direction r2. In this case, the pitch of the active
transistor cells can be chosen to be less than, equal to or greater
than the pitch of the portions 41, 42 of the patterned fourth
semiconductor zone 4.
[0048] In a departure from the exemplary embodiment in accordance
with FIGS. 2, 3 and 4, strips of active transistor cells formed in
strip-like fashion and portions 40, 41, 42 of the patterned fourth
semiconductor zone 4 which are formed in strip-like fashion can run
in different lateral directions, for example in the lateral
directions r1 and r2. In principle, however, the different lateral
directions r1, r2 can also form an angle that is different from
90.degree..
[0049] In principle, the cell structure of the totality of the
active transistor cells arranged in an active component portion
100a can be chosen independently of the cell structure of that
portion of the patterned fourth semiconductor zone 4 which is
arranged in the same active component portion 100a. Apart from
strip-like structures, by way of example, strip-like, reticulated,
lattice-like, meander-like, comb-like or comb-like intermeshing
structures are also suitable here in each case as cell
structures.
[0050] In order to further increase the reverse voltage strength of
the transistor or to achieve an additional reduction of the on
resistance, instead of only one patterned semiconductor zone, it is
also possible to provide two or more patterned semiconductor zones
which are doped complementarily to the second semiconductor zone 12
and are embedded into the second semiconductor zone 12 at a
distance from one another in the vertical direction v. In the off
state of the transistor, the different patterned semiconductor
zones that are at a distance from one another have different
electrical potentials lying in each case between the electrical
potentials of the third semiconductor zone 13 and the first
semiconductor zone 11.
[0051] FIG. 5 illustrates an exemplary embodiment in respect
thereof on the basis of a transistor having a p-doped patterned
fourth semiconductor zone 4 and a likewise p-doped patterned fifth
semiconductor zone 5.
[0052] In the same way as the patterned fourth semiconductor zone
4, the patterned fifth semiconductor zone 5 also has portions 51,
52 which are at a distance from one another in the first lateral
direction r1. A portion 126 of the drift zone 12 is respectively
arranged between in each case two adjacent portions from among the
portions 51, 52. The portions 51, 52 of the patterned fifth
semiconductor zone 5 can be formed in strip-like fashion, by way of
example. Instead of a strip-like structure, the second patterned
semiconductor zone 5 can also have some other structure, for
example a reticulated structure, a lattice-like structure, a
meander-like structure, a comb-like structure or a comb-like
intermeshing structure. In this case, the patterned fourth
semiconductor zone 4 and the patterned fifth semiconductor zone 5
can have different or identical types of structure. In the case of
identical types of structures, the latter can be oriented in the
same sense or be rotated relative to one another, for example with
respect to an axis running in the vertical direction v.
[0053] The patterned fifth semiconductor zone 5 is at a greater
distance from the front side 101 of the semiconductor body 100 than
the patterned fourth semiconductor zone 4. As already explained on
the basis of the exemplary embodiment in accordance with FIGS. 2 to
4, the patterned fourth semiconductor zone 4 is at an electrical
potential which, when the transistor is in the off state,
essentially corresponds to the electrical potential U.sub.4 which
the second semiconductor zone 12 has at a location 128 located
below a dielectric 26 of a first field electrode 961, which is
arranged in a trench and which delimits the active component
portion 100a toward the lateral edge 103 of the semiconductor body
100. Moreover, the patterned fourth semiconductor zone 4 is
connected to the first semiconductor zone 11 via the third
electrode 93 and also via two series-connected resistors 80a and
80b and via the second electrode 92. The overall resistor including
the series circuit of the resistors 80a and 80b corresponds--with
regard to its interconnection with the third electrode 93 and the
first semiconductor zone 11--to the resistor 80 in accordance with
FIG. 2.
[0054] Analogously to the patterned fourth semiconductor zone 4,
the patterned fifth semiconductor zone 5, when the transistor is in
the off state, is at an electrical potential essentially
corresponding to the potential U.sub.5 which the second
semiconductor zone 12 has at a location 228 situated at the lateral
edge of the active component portion 100a.
[0055] Thus, each of the two patterned semiconductor zones 4, 5,
when the transistor is in the off state, is at an electrical
potential lying between the electrical potential of the third
semiconductor zone 13 and the potential of the second semiconductor
zone 12 on that side of the respective patterned fourth or fifth
semiconductor zone 4 or 5 which faces the front side 101.
[0056] The electrical potential U.sub.5 is transferred to a fourth
electrode 94 via a tenth semiconductor zone 229 of the conduction
type of the second semiconductor zone 12 and via fifteenth
connection zones 32, which are of the same conduction type as the
tenth semiconductor zone 229 but doped more heavily than the
latter. The patterned fifth semiconductor zone 5 is electrically
connected to the fourth electrode 94, which is at a distance from
the electrodes 91 and 93, via an eleventh semiconductor zone
("sinker") 59 doped complementarily to the second semiconductor
zone 12. The patterned fourth semiconductor zone 4 and the
patterned fifth semiconductor zone 5 are thus at different
electrical potentials U.sub.4 and U.sub.5, respectively. The
eleventh semiconductor zone 59 can be doped in such a way that it
is not depleted at least in a portion situated between the fourth
electrode 94 and the layer 19, even at those voltages at which the
avalanche breakdown occurs at the pn junction formed between the
second semiconductor zone 12 and the third semiconductor zone
13.
[0057] The patterned fourth semiconductor zone 4 is arranged in a
layer 19 extending over the entire semiconductor body 100 in each
direction perpendicular to the vertical direction v. In accordance
with the space charge zone 29 in the layer 18, when the transistor
is in the off state, a space charge zone 39 also forms in the layer
19, the charge carriers of the second semiconductor zone 12 being
essentially depleted in the space charge zone, whereby the blocking
capability of the transistor can be increased and the on resistance
can be reduced.
[0058] In the case of the present exemplary embodiment, the
location 228 to which the second patterned semiconductor zone 5 is
connected lies at the lateral edge of the active component region
100a and directly below the patterned fourth semiconductor zone 4.
In an analogous manner it is possible to add to the transistor even
further patterned, p-doped semiconductor zones which are arranged
between the patterned fifth semiconductor zone 5 and the first
semiconductor zone 11 and which, when the transistor is in the off
state, are in each case connected to an electrical potential which
the second semiconductor zone 12 has at a location situated at the
lateral edge of the active component region 100a directly below the
patterned semiconductor zone closest to the further patterned
semiconductor zone in a direction of the front side 101.
[0059] The use of two or more of such patterned semiconductor zones
4, 5 which are arranged successively in the vertical direction v
and are doped complementarily to the second semiconductor zone 12
enables the reverse voltage strength of the transistor to be
improved as required. If two or more of such patterned
semiconductor zones 4, 5 are provided, the vertical distance d12
between adjacent patterned semiconductor zones 4, 5 can be chosen
for example to be identically equal to the vertical distance d01
between the trench bottoms of the gate electrodes 95 and the
patterned fourth semiconductor zone 4 nearest the gate electrodes
95. Likewise, the distances d01 and d12 can be chosen for example
such that they have a ratio d01/d12 of 0 (i.e. d01=0) to 1.
[0060] In the portions of the second semiconductor zone 12 which
are arranged between the portions of the patterned fourth
semiconductor zone 4 or between the portions of the patterned fifth
semiconductor zones 5, the net dopant concentration can amount for
example to 1.5 times to 100 times or 3 times to 30 times the net
dopant concentration which the second semiconductor zone 12 has in
the portions which, in the vertical direction v, downwardly and/or
upwardly adjoin the respective patterned fourth semiconductor zone
4 or fifth semiconductor zone 5.
[0061] If the product of the net dopant concentration in the
patterned semiconductor zone and the structure width thereof in the
lateral direction considered, here r1 for example, and the product
of the net dopant concentration in those portions of the second
semiconductor zone 12 which are arranged between the portions of
the patterned fourth semiconductor zone 4 and the structure width
of the portions of the second semiconductor zone 12 in the same
lateral direction with respect to one another have a ratio of 0.9
to 1.1, those portions of the second semiconductor zone 12 which
are arranged between the portions 40, 41, 42 of the patterned
fourth semiconductor zone 4 can be depleted. Otherwise, the
component must be operated in the J-FET operating mode. The same
relationship correspondingly holds true for one or a plurality of
further patterned semiconductor zones such as e.g., the patterned
semiconductor zone 5. In this case, the structure width is
understood to be the distance between mutually corresponding
locations of adjacent portions, here the portions 41, 42, of the
relevant patterned semiconductor zone, here the fourth
semiconductor zone 4. FIG. 5 illustrates by way of example a
structure width b given by the distance b measured in the lateral
direction r1 between those sides of the adjacent portions 41, 42 of
the patterned fourth semiconductor zone 4 which face the ninth
semiconductor zone 49.
[0062] In the case of the exemplary embodiment in accordance with
FIG. 5, the patterned fourth semiconductor zone 4 and the patterned
fifth semiconductor zone 5 have identical structure widths b in the
same lateral direction r1. In a departure from this, the structure
widths b of different patterned semiconductor zones 4 and 5 can
differ from one another.
[0063] Analogously to the structure widths b of patterned
semiconductor zones, structure widths of the transistor cells
arranged in the active component region 100a can also be determined
in each case in the lateral directions r1, r2. In this case, in the
same lateral direction, the structure width of the transistor cells
can be, as required, equal to, less than or greater than the
structure width of one or a plurality of the patterned
semiconductor zones 4, 5 of the component.
[0064] As can further be seen from FIG. 5, provision may be made
for providing a potential decoupling structure between two adjacent
sinkers 49, 59 which are a distance from one another in the first
lateral direction r1, which potential decoupling structure at least
partly shields the sinker 59, that is to say the eleventh
semiconductor zone 59, from the electric field issuing from the
sinker 49, that is to say the ninth semiconductor zone 49. Such a
potential decoupling structure can have for example a second and/or
a third or more field electrodes 962 and 963, respectively,
arranged in a trench, which are electrically insulated by using
dielectric 26 from the ninth semiconductor zone 49, from the
eleventh semiconductor zone 59 and from the tenth semiconductor
zone 229 arranged between the ninth semiconductor zone 49 and the
eleventh semiconductor zone 59. In the case of a semiconductor
component having at least two patterned semiconductor zones 4, 5
which are at a distance from one another in the vertical direction
v and which have different electrical potentials in the case of a
reverse voltage present at the semiconductor component, that one of
the electrodes 96 which is closest to the lateral edge 103 in a
predetermined lateral direction r1 can be connected to an
electrical potential lying between the electrical potentials of the
source electrode 91 and the drain electrode 92. As an alternative
to this, the field electrodes 961, 962, 963 of the component can
for example also all be arranged in floating fashion in the
semiconductor body 1.
[0065] Furthermore, it is possible to arrange the third field
electrode 963 for forming an edge structure between the lateral
edge 103 of the semiconductor body 100 and the sinker 59 closest to
the lateral edge 103. Furthermore, in the semiconductor body 100 it
is possible to provide a fourth field electrode 964, which is
arranged between the tenth semiconductor zone 229 and the eleventh
semiconductor zone 59, extends into the semiconductor body 100 in a
direction of the first semiconductor zone 11 proceeding from the
front side 101 and electrically decouples the tenth semiconductor
zone 229 from the eleventh semiconductor zone 59. Correspondingly,
it is possible to provide in the semiconductor body 100 a fifth
field electrode 965, which is arranged between the tenth
semiconductor zone 229 and the ninth semiconductor zone 49, extends
into the semiconductor body 100 in a direction of the first
semiconductor zone 11 proceeding from the front side 101, and
electrically decouples the ninth semiconductor zone 49 from the
front-side portion of the tenth semiconductor zone 229.
[0066] In order to prevent the connection resistance of a patterned
semiconductor zone 4, 5 from becoming too high, as an alternative
or in addition to a sinker 49, 59 arranged between the lateral edge
103 of the semiconductor body 100 and an active component portion
100a closest to the lateral edge 103, it is possible to provide one
or a plurality of further sinkers which are arranged between
adjacent active component portions and are connected to the
relevant sinker 49, 59.
[0067] As an exemplary embodiment in this respect FIG. 6
illustrates a portion of a transistor having only one patterned
fourth semiconductor zone 4. This transistor portion can be for
example a portion of the transistor in accordance with FIG. 2. The
transistor in accordance with FIG. 6 includes two adjacent active
component portions 100a, 100b which are at a distance from one
another in the first lateral direction r1. The ninth semiconductor
zone 49 is arranged between the active component portions 100a,
100b and connected to the patterned fourth semiconductor zone 4.
The ninth semiconductor zone 49 is provided in addition to the
ninth semiconductor zone 49 on the edge side that is illustrated in
FIG. 2. In the same way as the ninth semiconductor zone 49 in
accordance with FIG. 2 is connected to a third electrode 93 applied
to the semiconductor body 100, the ninth semiconductor zone 49 in
the case of the arrangement in accordance with FIG. 6 is connected
to a further third electrode 93, wherein these third electrodes 93
can be electrically conductively connected to one another or
electrically decoupled from one another. The third electrode 93 in
accordance with FIG. 6 is connected to another seventh
semiconductor zone 129 like the third electrode 93 in accordance
with FIG. 2.
[0068] FIGS. 7 and 8 illustrate further exemplary embodiments of
the vertical trench transistor explained with reference to FIGS. 2
to 4. In contrast to the transistor in accordance with FIG. 2, the
transistors in accordance with FIGS. 7 and 8 have pn junctions
having a low breakdown or punch voltage, which prevent, when the
transistor is in the off state, charge carriers from being injected
into that portion of the second semiconductor zone 12 which is
closest to the seventh semiconductor zone 129.
[0069] Thus, the transistor in accordance with FIG. 7 is provided
with a thirteenth semiconductor zone 33, which is doped
complementarily to the seventh semiconductor zone 129, is arranged
between the third electrode 93 and the seventh semiconductor zone
129 and is connected to the third electrode 93, and together with
the seventh semiconductor zone 129 forms a pn junction.
[0070] In the case of the transistor in accordance with FIG. 8, a
fourteenth semiconductor zone 34 is also arranged between the
thirteenth semiconductor zone 33 and the third electrode 93,
wherein the fourteenth semiconductor zone 34 has the conduction
type of the seventh semiconductor zone 129 and can be doped more
heavily than the latter. The fourteenth semiconductor zone 34 is
connected to the third electrode 93 and together with the
thirteenth semiconductor zone 33 forms a pn junction. The
thirteenth semiconductor zone 33 in turn forms a pn junction with
the seventh semiconductor zone 129 and is likewise connected to the
third electrode 93. Moreover, the fourteenth semiconductor zone 34
is at a distance from the seventh semiconductor zone 129.
[0071] As a further exemplary embodiment FIG. 9 illustrates a
trench transistor in which the potential control structure includes
a first diode 81, the anode of which is electrically connected to
the source electrode 91 and the cathode of which is electrically
connected to the patterned fourth semiconductor zone 4 via the
ninth semiconductor zone 49. When the transistor is in the off
state, the electrical potential of the patterned fourth
semiconductor zone 4 is essentially determined by the voltage drop
across the first diode 81. While the potential U.sub.4 in the case
of the exemplary embodiment in accordance with FIG. 1, when the
component is in the off state, changes depending on the voltage
difference present between the anode terminal A and the cathode
terminal K, the potential U.sub.4 in the case of the exemplary
embodiment in accordance with FIG. 9 can be independent of the
voltage difference between the source terminal and the drain
terminal, for example if the first diode 81 is a zener diode having
a predetermined breakdown voltage and a reverse voltage present
between the electrodes 91, 92 is higher than the breakdown voltage
of the first diode 81. The first diode 81 can be integrated into
the semiconductor body 100 or be arranged outside the semiconductor
body 100. In order to produce a higher voltage drop, two or more
further diodes can also be connected in series with the first diode
81.
[0072] Since the electrical potential fed to the patterned fourth
semiconductor zone 4 is concomitantly determined by the first diode
81, a seventh semiconductor zone 129, such as is illustrated for
example in the case of the arrangement in accordance with FIG. 2,
can be dispensed with given suitable dimensioning. In order to
electrically decouple the ninth semiconductor zone 49 from the
front-side portion of the second semiconductor zone 12, a sixth
field electrode 966 is provided, which is arranged between the
ninth semiconductor zone 49 and the second semiconductor zone 12
and extends into the semiconductor body 100 in a direction of the
first semiconductor zone 11 proceeding from the front side 101.
[0073] It is likewise possible, as is illustrated in FIG. 10,
analogously to the exemplary embodiment in accordance with FIG. 5,
to provide two or more patterned fourth and fifth semiconductor
zones 4, 5, respectively, the potential difference of which is set
by using a respective second diode 82. The patterned fourth
semiconductor zone 4 is connected to the third semiconductor zone
13 via the ninth semiconductor zone 49, via the third electrode 93,
via the first diode 81 and via the source electrode 93, as was
explained on the basis of the exemplary embodiment in accordance
with FIG. 9. A patterned fifth semiconductor zone 5 is connected to
the third electrode 93 via an eleventh semiconductor zone 59 formed
as a sinker, via a fourth electrode 94 applied to the semiconductor
body 100 on the front side, and via a second diode 82, wherein the
anode of the second diode 82 is connected to the third electrode 93
and the cathode of the second diode 82 is connected to the fourth
electrode 94. Consequently, the potential difference present
between the patterned fourth semiconductor zone 4 and the patterned
fifth semiconductor zone 5 when the transistor is in the off state
is essentially determined by the voltage dropped across the second
diode 82. Instead of being connected to the third electrode 93, the
anode of the second diode 82 can also be connected to the first
electrode 91. In order to electrically decouple the ninth
semiconductor zone 49 and the eleventh semiconductor zone 59 from
one another, it is possible to provide in the semiconductor body
100 a seventh field electrode 967, which is arranged between the
ninth semiconductor zone 49 and the eleventh semiconductor zone 59
and extends into the semiconductor body 100 in a direction of the
first semiconductor zone 11 proceeding from the front side 101.
[0074] In a corresponding manner, further patterned semiconductor
zones of the conduction type of the patterned fourth or fifth
semiconductor zone 4, 5 can be provided between the patterned fifth
semiconductor zone 5 and the first semiconductor zone 11, wherein a
further patterned semiconductor zone can be connected, by using a
further diode, to another patterned semiconductor zone which is
arranged between the source zone and the further patterned
semiconductor zone. In this case, the diode can be connected to
electrodes, one of which is electrically connected to the further
patterned semiconductor zone via a sinker of the conduction type of
the further semiconductor zone and the other of which is
electrically connected to the other patterned semiconductor zone
via another sinker of the conduction type of the other patterned
semiconductor zone.
[0075] In an individual case it may be necessary, in a component
arrangement, to choose relatively small distances for adjacent
portions of a patterned semiconductor zone. This may have the
consequence that dopants used for doping the patterned
semiconductor zone, in the event of a temperature increase such as
may occur during processing and/or during operation of the
transistor, diffuse into a portion of the drift zone which is
arranged between adjacent portions of the patterned semiconductor
zone, whereby a significant lowering or even an inversion of the
original doping can occur in the portion of the drift zone owing to
the comparatively high dopant concentration in the patterned
semiconductor zone. In order to avoid this, provision may be made
for doping portions of the drift zone which are arranged between
adjacent portions of the patterned semiconductor zone with a dopant
which has only a low tendency toward thermal diffusion in
comparison with conventional dopants.
[0076] This is illustrated in FIG. 11 on the basis of a vertical
section through a transistor portion. The construction of this
transistor portion corresponds, in principle, to the transistor
portion in accordance with FIG. 2. The sectional view illustrated
reproduces a section through the sectional plane V2 in accordance
with FIG. 12.
[0077] The transistor in accordance with FIG. 11 has a patterned
fourth semiconductor zone 4 having portions 40, 41, 42 which are at
a distance from one another. A portion of a second semiconductor
zone 12 is respectively arranged between adjacent portions 41, 42.
Moreover, twelfth semiconductor zones 120 are arranged in the layer
18 between adjacent portions 40, 41, 42 of the patterned fourth
semiconductor zone 4, the twelfth semiconductor zones being formed
by portions 120 of the second semiconductor zone 12. The twelfth
semiconductor zones 120 are doped with arsenic, which has an
n-doping effect in silicon and has only a low tendency toward
thermal diffusion.
[0078] As an alternative to this, the layer 18 (also the layer 19
in the case of the arrangement in accordance with FIG. 10) can also
be produced as a p-doped epitaxial layer in which n-doped islands
are produced by using a masked implantation of arsenic. The islands
then correspond to the twelfth semiconductor zones 120 illustrated
in FIG. 11 and, in a departure from the arrangement in accordance
with FIG. 11, can also extend in the lateral direction r1 as far as
the patterned fourth semiconductor zone 4 (or as far as the
patterned semiconductor zone 4 and/or as far as the patterned
semiconductor zone 5 in FIG. 10).
[0079] In the case of a transistor whose construction corresponds
to the transistor in accordance with FIG. 2 but which is doped
complementarily, that is to say in which p-doped semiconductor
zones are provided instead of the n-doped semiconductor zones
illustrated in FIG. 11 and in which n-doped semiconductor zones are
provided instead of the p-doped semiconductor zones illustrated in
FIG. 11, the patterned fourth semiconductor zone 4 itself can be
doped with arsenic, such that regions which are arranged
analogously to the regions 120 in accordance with FIG. 11 in the
layer 18 of the patterned fourth semiconductor zone 4 but are
p-doped can then be dispensed with.
[0080] As an alternative to this, the layer 18 in the case of a
complementarily doped component, that is to say in which, inter
alia, the second semiconductor zone 12 is p-doped and the patterned
fourth semiconductor zone 4 and the patterned fifth semiconductor
zone 5 are n-doped, can also be produced as a p-doped epitaxial
layer in which the n-doped patterned fourth and fifth semiconductor
zones 4 and 5, respectively, are produced by using a masked
implantation of arsenic into the p-doped epitaxial layer. In the
case of such a complementarily doped component, portions which
correspond to the twelfth semiconductor zones 120 in accordance
with FIG. 11 but are p-doped can be dispensed with.
[0081] FIG. 12 illustrates a horizontal section in a sectional
plane B2 illustrated in FIG. 11, the sectional plane being
perpendicular to the vertical direction v. It can be seen from this
horizontal section, in conjunction with FIG. 11, that the second
semiconductor zone 12 and the arsenic-doped portions 120 penetrate
through the patterned fourth semiconductor zone 4 in pillar-like
fashion. The arsenic-doped portions 120 can be at a distance from
the patterned fourth semiconductor zone 4, as illustrated, but can
also in a departure from the illustration in FIGS. 11 and 12
directly adjoin the patterned fourth semiconductor zone 4. The
arsenic-doped twelfth semiconductor zones 120 stabilize the second
semiconductor zone 12 in the layer 18 of the patterned fourth
semiconductor zone 4. In a corresponding manner, such twelfth
semiconductor zones 120 which stabilize the doping of the second
semiconductor zone 12 can also be provided between portions of
further patterned semiconductor zones, for example between portions
51, 52 of the patterned fifth semiconductor zone 5, as is known
from the transistor in accordance with FIG. 5.
[0082] Various processes for producing a trench transistor in
accordance with FIG. 5 are explained below with reference to FIGS.
13A to 13J. On the basis thereof, the person skilled in the art is
also able, through suitable modifications of the method, to produce
other components having a patterned semiconductor zone which, in
the off state of the component, is connected to an electrical
potential lying between potentials present at the component.
[0083] In accordance with FIG. 13A, the first process involves
providing a heavily n-doped substrate 11 having a semiconductor
basic material, for example silicon or silicon carbide, which later
forms the first semiconductor zone 11 of the transistor. If the
component to be produced is an IGBT, however, a heavily p-doped
substrate 11 must be used instead of the heavily n-doped substrate
11. A weakly n-doped layer 121 is applied, for example epitaxially,
to the substrate, the result of which is illustrated in FIG. 13B.
As an alternative to the processes in accordance with FIGS. 13A and
13B, there is also the possibility of providing a weakly n-doped
substrate and of producing the heavily n-doped semiconductor zone
11 on the rear side by diffusion and/or implantation of suitable
dopants.
[0084] Mask 71 is applied to the arrangement in accordance with
FIG. 13B and patterned. Using this patterned mask 71, a dopant 105
is implanted into the weakly n-doped layer 121, which dopant, in
the semiconductor basic material used, brings about a doping
complementarily to the doping of the second semiconductor zone 12
of the component to be produced. The implantation is carried out in
such a way that the doping of the original layer 121 is inverted,
thus giving rise to portions 50, 51 and 52 doped complementarily to
the n-doped layer 121, which is illustrated in FIG. 13C. In
principle, a diffusion could also be provided instead of an
implantation, but this results in softer pn junctions between the
layer 121 and the portions 50, 51, 52 produced therein. After the
removal of the mask 71, a layer 122 of the conduction type of the
second semiconductor zone 12 to be produced is applied, for example
epitaxially, to this arrangement on the front side, the result of
which is illustrated in FIG. 13D. Using a further patterned mask
72, which is applied to the arrangement in accordance with FIG. 13D
on the front side, dopants 105 are again implanted, as illustrated
in FIG. 13E, into the semiconductor body constructed up to that
point, such that a p-doped semiconductor zone 591 arranged above
the semiconductor zone 50 arises. The dopant 105 can have the same
properties as the dopant 105 already described with reference to
FIG. 13D.
[0085] After the removal of the mask 72, a further layer 123 of the
conduction type of the second semiconductor zone 12 to be produced
is produced, for example epitaxially, on the front side, the result
of which is illustrated in FIG. 13F. After using a further
patterned mask 73 applied to the front side of this arrangement,
dopants 105 are implanted in the semiconductor body constructed up
to that point, thus giving rise to semiconductor zones 592, 40, 41,
42 doped complementarily to the doping of the second semiconductor
zone 12 to be produced. In this case, the semiconductor zone 592 is
produced above the semiconductor zone 591. The dopant 105 can have
the same properties as the dopant 105 explained with reference to
FIGS. 13C and 13E. FIG. 13G illustrates the arrangement during the
implantation of the dopant 105. After the removal of the patterned
mask 73, a layer 124 of the conduction type of the second
semiconductor zone 12 to be produced is applied, for example
epitaxially, on the front side to the semiconductor body
constructed up to that point, the result of which is illustrated in
FIG. 13H.
[0086] Afterward, using a patterned mask 74 applied on the front
side, a dopant 105 is implanted into the semiconductor body
constructed up to that point, in order to produce further p-doped
semiconductor zones 593 and 49. In this case, the semiconductor
zone 593 is produced above the semiconductor zone 592 and the
semiconductor zone 49 is produced above the portion 40. The dopant
105 can have the same properties as the dopant 105 explained with
reference to FIGS. 13C, 13E and 13G. FIG. 13I illustrates the
arrangement during the implantation of the dopant 105. Removal of
the patterned mask 74 yields the semiconductor body 100 illustrated
in FIG. 13J with the patterned fourth semiconductor zone 4
including the portions 40, 41, 42, with the sinker 49 connected to
the portion 40 of the patterned fourth semiconductor zone 4, with
the patterned fifth semiconductor zone 5 including the portions 50,
51, 52, and with the sinker 59 connected to the portion 50 of the
patterned fifth semiconductor zone 5.
[0087] In the case of the exemplary embodiment explained with
reference to FIGS. 13A to 13J, semiconductor zones 50, 591, 592 and
593 which lie one above another, adjoin one another and form a
continuous p-doped semiconductor zone were produced in order to
form a sinker 59 connected to the patterned fifth semiconductor
zone 5. Correspondingly, semiconductor zones 40 and 49 which lie
one above another and adjoin one another were produced in order to
form a sinker 49 connected to the patterned fourth semiconductor
zone 4. In a departure from the exemplary embodiment explained,
adjacent semiconductor zones 50, 591, 592, 593 and 40, 49 can
initially also be produced at a distance from one another. By using
a subsequent heat treatment process they can be subjected to
outdiffusion and enlarged in the process, such that the adjacent
semiconductor zones 50 with 591, 592 and 593, and 40 with 49 grow
together and continuous p-doped semiconductor zones arise.
[0088] In the semiconductor body 100 illustrated in FIG. 13J, it is
then possible, in a manner known per se, to produce the active
region--illustrated in FIG. 5 with the third semiconductor zone 13,
the sixth semiconductor zone 16, the gate dielectric 25, and also
the gate electrodes 95, and to apply the electrodes 91 and 92. In
this case, a larger thickness can be chosen for the dielectric 26
than for the gate dielectric 25. The production of the eighth
semiconductor zone 31 and of the fifteenth semiconductor zone 32
can take place at the same time as the production of the third
semiconductor zone 13, wherein a conventional patterned mask used
for producing the third semiconductor zone 13 must be provided with
openings at the corresponding locations above the semiconductor
zones 31, 32 to be produced. The production of the third and/or
fourth electrode 93 and/or 94, respectively, can take place in the
same process as the production of the first electrode 91 and/or of
the second electrode 92, wherein trenches reaching into the
semiconductor material of the semiconductor body 100 as far as
below the dielectric layer 27 must additionally be produced before
the application of the electrode material. The electrodes 91, 92,
93, 94 can be formed for example as metallizations of the
semiconductor body 100 and for example be composed of aluminum or
have aluminum. As an alternative, the electrodes 91, 92, 93, 94 can
for example also have or be composed of highly doped
polycrystalline semiconductor material, e.g., highly doped
polycrystalline silicon.
[0089] In the case of the exemplary embodiments explained above
with reference to FIGS. 1 to 8, 11 and 12, first field electrodes
961 are provided which delimit the active component region 100a
toward the lateral edge 103. The electrical potential present when
the component is in the off state in the second semiconductor zone
12 directly below the first field electrodes 961 at the locations
128 is fed to the patterned fourth semiconductor zone 4 by using a
seventh semiconductor zone 129, which is decoupled by the first
field electrode 961 from the active component region 100a and thus
from the third semiconductor zone 13 and also from the front-side
portion of the second semiconductor zone 12 that is situated
laterally alongside the first field electrode 961.
[0090] In principle, however, it is also possible to produce the
electrical potential that is to be fed to a patterned fourth or
fifth semiconductor zone when the component is in the off state
without the use of such first field electrodes 961 and without the
use of such seventh semiconductor zones 129, which is explained
below on the basis of various examples with reference to FIGS. 14,
15 and 16.
[0091] FIG. 14 illustrates a vertical section through a planar
diode. The planar diode includes a semiconductor body 100, in which
a heavily doped first semiconductor zone 11 of the first conduction
type, a weakly doped second semiconductor zone 12 of the first
conduction type, and also a third semiconductor zone 13 of the
second conduction type are arranged successively in a vertical
direction v. The planar diode includes an active component region
100a, the lateral dimensions of which in all lateral directions r1,
r2 perpendicular to the vertical direction v are defined by the
lateral dimensions of the third semiconductor zone 13 forming the
anode.
[0092] A first electrode 91 applied to the front side 101 is
provided for making contact with the third semiconductor zone 13. A
dielectric layer 27 is arranged between the front side 101 and the
first electrode 91. Extensions of the first electrode 91 penetrate
through the dielectric layer 27 and make contact with the
semiconductor body 100 at the front side 101 in the region of the
third semiconductor zone 13. A continuous second electrode 92 is
applied to the rear side 102 for the purpose of making contact with
the first semiconductor zone 11.
[0093] In the vertical direction v, a patterned fourth
semiconductor zone 4 of the second conduction type is arranged
between the first semiconductor zone 11 and the third semiconductor
zone 13, which fourth semiconductor zone can be constructed in the
same way as a patterned fourth semiconductor zone 4 explained on
the basis of the previous exemplary embodiments. In the present
case, the patterned fourth semiconductor zone 4 has portions 40,
41, 42 which are arranged at a distance from one another in the
first lateral direction r1. A portion 125 of the second
semiconductor zone 12 is respectively arranged between adjacent
portions from among the portions 40, 41, 42.
[0094] In order to feed to the patterned fourth semiconductor zone
4 in the illustrated off state of the planar diode an electrical
potential lying between the electrical potential of the first
semiconductor zone 11 and the electrical potential of the third
semiconductor zone 13, a potential control structure is provided
which includes a zener diode 33, 34, a third electrode 93 and also
a ninth semiconductor zone 49 of the second conduction type.
[0095] The zener diode 33, 34 includes a thirteenth semiconductor
zone 33 of the second conduction type, which together with the
second semiconductor zone 12 forms a pn junction. Furthermore, the
zener diode 33, 34 includes a fourteenth semiconductor zone 34 of
the first conduction type, which is at a distance from the second
semiconductor zone 12 and together with the thirteenth
semiconductor zone 34 forms the pn junction of the zener diode 33,
34.
[0096] The third electrode 93 makes contact with the fourteenth
semiconductor zone 34 and transfers the electrical potential
present there to the ninth semiconductor zone 49, which is formed
as a sinker and which is additionally connected to the portion 40
and thus to the patterned fourth semiconductor zone 4. The doping
of the ninth semiconductor zone 49 is chosen in such a way that it
is not depleted, at least in a portion located between the third
electrode 93 and the layer 18 of the patterned fourth semiconductor
zone 4 in the vertical direction v, even at those voltages at which
the avalanche breakdown occurs at the pn junction formed between
the second semiconductor zone 12 and the third semiconductor zone
13.
[0097] In the transition of the planar diode from the illustrated
off state to the on state, the potential control structure serves
moreover to discharge the patterned fourth semiconductor zone 4
that is charged when the planar diode is in the off state.
[0098] While in the exemplary embodiments explained above the ninth
semiconductor zone 49 extends approximately as far as the upper
edge of the semiconductor layer 18 containing the patterned fourth
semiconductor zone 4 and is connected to the portion 40 there, the
ninth semiconductor zone 49 in the exemplary embodiment in
accordance with FIG. 14 extends by way of example over the entire
height of the semiconductor layer 18. In general, in this case and
in other components, however, it suffices for the ninth
semiconductor zone 49 to make contact with the patterned fourth
semiconductor zone 4, for example the portion 40 thereof.
[0099] The planar diode illustrated has moreover a seventh
electrode 97 and an eighth electrode 98, which are in each case
optional and formed as field plates. The seventh electrode 97 and
the eighth electrode 98 are in each case at a distance from the
semiconductor body 100 and electrically insulated from the latter
by the dielectric layer 27. The seventh electrode 97 is connected
to the first electrode 91. The seventh electrode 97 can be arranged
for example in the vertical direction v above the geometrical
location at which the pn junction between the second semiconductor
zone 12 and the third semiconductor zone 13 leads to the surface
101 of the semiconductor body 100. Proceeding from the geometrical
location, the seventh electrode 97 can extend in a direction of the
lateral edge 103. The eighth electrode 98 is connected to the third
electrode 93 and, proceeding from the latter, extends in a
direction of the lateral edge 103. When the planar diode is in the
off state, the seventh electrode 97 and/or by the eighth electrode
98 ensure that a maximum permissible gradient of the electrical
potential for an edge termination is complied with.
[0100] In the case of the arrangement in accordance with FIG. 14, a
first diode 81 is furthermore illustrated, which can be provided to
the zener diode 33, 34. The first diode 81 is connected between the
third semiconductor zone 13 and the patterned fourth semiconductor
zone 4 in such a way that it is reverse-biased when the component
is in the off state. For this purpose, as illustrated by way of
example in the arrangement in accordance with FIG. 14, the anode of
the first diode 81 can be electrically connected to the first
electrode 91 and the cathode of the first diode 81 can be
electrically connected to the third electrode 93.
[0101] When the zener diode 33, 34 is dispensed with, the doping of
the semiconductor zones 33 and 34 can be replaced by a weak doping
of the first conduction type. When the zener diode 33, 34 is
dispensed with, moreover, the extension 931 of the third electrode
93 which penetrates through the dielectric layer 27 is
unnecessary.
[0102] The exemplary embodiment in accordance with FIG. 15
illustrates a vertical section through a planar diode which, apart
from the configuration of the third semiconductor zone 13, can be
constructed in the same way as the planar diode explained with
reference to FIG. 14. In the case of the planar diode in accordance
with FIG. 15, the third semiconductor zone 13 is patterned and has
portions 131, 132 which are electrically connected to one another.
Contact is made with each of the portions 131, 132 by an extension
of the first electrode 91. The third semiconductor zone 13 can have
for example a reticulated or lattice-like structure. As an
alternative thereto, other structures, e.g., strip-like,
meander-like, comb-like or comb-like intermeshing structures, are
also conceivable. What is crucial is that the third semiconductor
zone 3 pervades the second semiconductor zone 12 sufficiently
densely.
[0103] FIG. 16 illustrates a vertical section through a planar
transistor, the basic construction of which corresponds to that of
the planar diode in accordance with FIG. 15. In addition, the
planar transistor has a patterned sixth semiconductor zones 16 of
the second conduction type, which represents the body zones of the
planar transistor. The third semiconductor zone 13, which is
likewise patterned and forms the source zone of the transistor, is
at a distance from the second semiconductor zone 12, makes contact
with the first electrode 91 and together with the third
semiconductor zone 13 forms a pn junction.
[0104] Gate electrodes 95 are arranged above portions in which the
sixth semiconductor zone 16 extends between the second
semiconductor zone 12 and the third semiconductor zone 13 as far as
the front side 101, which gate electrodes are at a distance from
the semiconductor body 100 and are electrically insulated from the
latter by using the dielectric 27. As is usual in transistors with
a cell structure, the gate electrodes 95 serve for driving
individual transistor cells and are electrically conductively
connected to one another--not discernible in FIG. 16.
[0105] In the same way as in the trench components illustrated in
FIGS. 5 and 10, in accordance with the patterned fourth and fifth
semiconductor zone 4, 5 provided there, it is also possible, in a
planar component such as is illustrated e.g., in FIGS. 14 to 16, to
provide between the patterned fourth semiconductor zone 4 and the
first semiconductor zone 11 one or a plurality of further patterned
semiconductor zones which are at a distance from one another and
also from the patterned fourth semiconductor zone 4 and from the
first semiconductor zone 11. This is explained by way of example on
the basis of a planar transistor in accordance with FIG. 17 with
two patterned semiconductor zones 4 and 5.
[0106] In contrast to the planar transistor in accordance with FIG.
16, the planar transistor in accordance with FIG. 17 additionally
has a p-doped patterned fifth semiconductor zone 5, which is
arranged between the first semiconductor zone 11 and the patterned
fourth semiconductor zone 4 and is at a distance from the first
semiconductor zone 11 and also from the patterned fourth
semiconductor zone 4. The patterned fifth semiconductor zone 5
includes portions 50, 51, and also further portions (not
illustrated) which are at a distance from one another.
[0107] In order to feed to the patterned fourth semiconductor zone
4 in the illustrated off state an electrical potential lying
between the electrical potential of the first semiconductor zone 11
and the electrical potential of the patterned fourth semiconductor
zone 4, a second potential control structure is provided, which
includes a zener diode 36, 37, a fourth electrode 94, and also an
eleventh semiconductor zone 59 of the second conduction type.
[0108] The zener diode 37, 36 includes an n-doped sixteenth
semiconductor zone 36 and also a p-doped seventeenth semiconductor
zone 37, which together with the sixteenth semiconductor zone 36
forms the pn junction of the zener diode 36, 37.
[0109] The fourth electrode 94 makes contact with the sixteenth
semiconductor zone 36 and transfers the electrical potential
present there to the eleventh semiconductor zone 59, which is
formed as a sinker and which is additionally connected to the
portion 50 and thus to the patterned fifth semiconductor zone 5.
The doping of the eleventh semiconductor zone 59 is chosen in such
a way that it is not depleted, at least in a portion located in the
vertical direction v between the fourth electrode 94 and the layer
19 of the patterned fifth semiconductor zone 5, even at those
voltages at which the avalanche breakdown occurs at the pn junction
formed between the second semiconductor zone 12 and the third
semiconductor zone 13.
[0110] In the transition of the planar transistor from the
illustrated off state to the on state, the second potential control
structure serves moreover to discharge the patterned fifth
semiconductor zone 5 which is charged when the planar transistor is
in the off state.
[0111] The planar transistor illustrated has moreover an optional
ninth electrode 99, which is connected to the fourth electrode 94
and, proceeding from the latter, extends in a direction of the
lateral edge 103. The ninth electrode 99 is formed as a field
plate, is at a distance from the semiconductor body 100 and is
electrically insulated from the latter by the dielectric layer 27.
As part of an edge termination of the transistor, the ninth
electrode 99 together with the seventh and eighth electrode 97 and
98, respectively, ensures that a maximum permissible gradient of
the electrical potential which is required for an edge termination
is complied with.
[0112] The first diode 81 illustrated in FIGS. 15 to 17, which
diode can be provided to the zener diode 33, 34, corresponds to the
first diode 81 in accordance with FIG. 14, such that the statements
in respect thereof are correspondingly applicable.
[0113] The arrangement in accordance with FIG. 17 additionally
illustrates a second diode 82, which can be provided to the zener
diode 36, 37. The second diode 82 is connected between the
patterned fourth semiconductor zone 4 and the patterned fifth
semiconductor zone 5 in such a way that it is reverse-biased when
the component is in the off state. For this purpose, as is
illustrated by way of example in the arrangement in accordance with
FIG. 17, the anode of the second diode 82 can be electrically
connected to the third electrode 93 and the cathode of the second
diode 82 can be electrically connected to the fourth electrode
94.
[0114] When the zener diode 36, 37 is dispensed with, the doping of
the semiconductor zones 36 and 37 can be replaced by a weak doping
of the first conduction type. Moreover, when the zener diode 36, 37
is dispensed with, the extension 941 of the fourth electrode 94
which penetrates through the dielectric layer 27 is
unnecessary.
[0115] In the components illustrated in the exemplary embodiments
above, including the methods explained, the dopings can also be
interchanged, that is to say that p-doped semiconductor zones are
replaced by n-doped semiconductor zones and n-doped semiconductor
zones are replaced by p-doped semiconductor zones. In association
with this, p-doping dopants must be replaced by n-doping dopants
and n-doping dopants must be replaced by p-doping dopants and the
signs of the voltages present at the component must be
interchanged. Furthermore, in the case of diodes, anode and cathode
are to be interchanged. Moreover, it is possible for all the
embodiments explained on the basis of the examples above also to be
analogously applied to any other components having a second
semiconductor zone 12 formed as a drift zone, provided that this is
not ruled out by the respective type of the component.
[0116] Although specific embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that a variety of alternate and/or equivalent
implementations may be substituted for the specific embodiments
shown and described without departing from the scope of the present
invention. This application is intended to cover any adaptations or
variations of the specific embodiments discussed herein. Therefore,
it is intended that this invention be limited only by the claims
and the equivalents thereof.
* * * * *